Objective: To verify anti-experimental autoimmune neuritis(EAN) activity of dregs in Yisui Tongjing prescription after being extracted by ethanol and optimize its extraction process. Method: EAN rats model was established,then these rats divided into model group,immunoglobulin group,administration group,these rats were administered by the corresponding method,pathomorphological ultrastructure of rats peripheral nerve was observed by electron microscope.With comprehensive score of dry extract quality and yield of protein as index,orthogonal test was adopted to optimize extraction process of water-soluble constituents in Yisui Tongjing prescription with the amount of water,extraction time and times as factors. Result: The situation of demyelination of the administration group was significantly improved,the structure of myelinated fibers myelin lamellar was neat,at the same time you could still see the change in aggregation of collagen fibers and the newborn myelinated nerve fibers.The best extraction process for water-soluble constituents in Yisui Tongjing prescription was:extracted 3 times with 8 times the amount of water for 3 h each time. Conclusion: Water-soluble constituents in Yisui Tongjing prescription had treatment effect for EAN;This optimized extraction technology was simple,stable and suitable for industrial production.